Hyperphosphatemia secondary to chronic kidney disease is a very serious
condition, causing cardiovascular morbidity and mortality. Unfortunately,
currently available drugs have limited therapeutic effects. Hence, there is an
urgent need for more effective medications. The aim of this study was to
investigate the efficacy and safety of a new maghemite-based phosphate
adsorbent, known as C-PAM-11, which was developed by the Experimental
Radiology Section of Charité - Universitätsmedizin Berlin. The investigation
was conducted as a four-week feeding trial was carried out. Healthy Sprague
Dawley rats were fed a standard rat diet supplemented with the phosphate
adsorbent over a period of four weeks. Once a week, they were housed in
individual metabolic cages for 24 hours to collect urine and feces and measure
food uptake. At the end of the study, the rats were sacrificed and blood,
bones and organs were collected. Untreated control animals as well as animals
treated with the current gold standard, Renvela® (Sevelamer carbonate), served
as reference. Efficacy parameters were changes in urinary phosphate excretion,
serum phosphate concentration and bone structure. Safety was assessed by
observation of animals’ general condition, blood tests, and histologic
examination of organ sections. After four weeks of treatment, renal phosphate
excretion was drastically decreased. In addition, the serum phosphate
concentration was diminished to such an extent that the C-PAM-11 treated
animals developed hypophosphatemia. In contrast, the reference drug Renvela®
did not lower the serum phosphate concentration. HRpQCT analysis of the bones
also revealed the high efficacy of C-PAM-11. The different parameters measured
showed that the animals developed osteomalacia. In summary, the striking
effects observed in our study demonstrate the high efficacy of CPAM-11
treatment. More studies will follow to prove the effectiveness in animals with
renal insufficiency and to identify a clinically applicable dose. The present
study also shows good safety features of the new phosphate absorbent. Long-
term experiments will follow to rule out toxicity through iron accumulation.